﻿using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace WarNov.AesManagedWrapper
{
    public static class RMWCrypto
    {
        private static byte[] _salt = Encoding.UTF8.GetBytes(@"tQ?)&%d(&>96432___???()/&)(&)(&w\7^(4[?7u");

        public static string EncryptStringAES(string plainText, string sharedSecret)
        {
            if (string.IsNullOrEmpty(plainText))
                throw new ArgumentNullException("plainText");
            if (string.IsNullOrEmpty(sharedSecret))
                throw new ArgumentNullException("sharedSecret");
            string outStr = null;
            // Encrypted string to return
            AesManaged aesAlg = null;
            // AesManaged object used to encrypt the data
            try
            {
                // generate the key from the shared secret and the salt
                Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(sharedSecret, _salt);
                // Create a AesManaged object
                // with the specified key and IV.
                aesAlg = new AesManaged();
                aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);
                aesAlg.IV = key.GetBytes(aesAlg.BlockSize / 8);
                // Create a decrytor to perform the stream transform.
                ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
                // Create the streams used for encryption.
                using (MemoryStream msEncrypt = new MemoryStream())
                {
                    using (CryptoStream csEncrypt =
                        new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                        {
                            //Write all data to the stream.
                            swEncrypt.Write(plainText);
                        }
                    }
                    outStr = Convert.ToBase64String(msEncrypt.ToArray());
                }
            }
            finally
            {
                // Clear the AesManaged object.
                if (aesAlg != null)
                    aesAlg.Clear();
            }
            // Return the encrypted bytes from the memory stream.
            return outStr;
        }

        public static string DecryptStringAES(string cipherText, string sharedSecret)
        {
            if (string.IsNullOrEmpty(cipherText))
                throw new ArgumentNullException("cipherText");
            if (string.IsNullOrEmpty(sharedSecret))
                throw new ArgumentNullException("sharedSecret");
            // Declare the AesManaged object
            // used to decrypt the data.
            AesManaged aesAlg = null;
            // Declare the string used to hold
            // the decrypted text.
            string plaintext = null;
            try
            {
                // generate the key from the shared secret and the salt
                Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(sharedSecret, _salt);
                // Create a AesManaged object
                // with the specified key and IV.
                aesAlg = new AesManaged();
                aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);
                aesAlg.IV = key.GetBytes(aesAlg.BlockSize / 8);
                // Create a decrytor to perform the stream transform.
                ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
                // Create the streams used for decryption.
                byte[] bytes = Convert.FromBase64String(cipherText);
                using (MemoryStream msDecrypt = new MemoryStream(bytes))
                {
                    using (CryptoStream csDecrypt =
                        new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                    {
                        using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                            // Read the decrypted bytes from the decrypting stream
                            // and place them in a string.
                            plaintext = srDecrypt.ReadToEnd();
                    }
                }
            }
            finally
            {
                // Clear the AesManaged object.
                if (aesAlg != null)
                    aesAlg.Clear();
            }
            return plaintext;
        }
    }
}